My elderly father is now soiling, urinating in his clothing, and has peed on bathroom floor?

Yes, as cwillie mentioned, he could be having prostate problems. Prostate problems can lead to urinary retention and, paradoxically, people who have urinary retention also can have sudden, uncontrolled urination.

Chinaman, here are some more excellent ideas. https://www.agingcare.com/Incontinence

Get him in to his doctor for a checkup. Old men often have prostate difficulties, or he may even have a UTI. The fact he is missing the toilet makes me think he knows he has to go, but the need is so strong that he often can't get to the bathroom in time or can't get to the toilet before his stream starts. In the meantime check out some of the incontinence briefs, they are no longer obvious, bulky, rustling embarrassments.

It sounds like your dad may be incontinent. Get some Depends briefs for him and remind him every couple of hours to use the bathroom. If you can, go with him to make sure he uses the bathroom. And keep an eye on the briefs so he isn't sitting around in soiled pants.